For certain applications, a forwarding element (i.e., a switch, router, etc.) may receive packets that need to be forwarded to different destinations, because the different destinations will have process the data contained in the packets. One such application is high-frequency trading, in which high-performance servers analyze market data packets (that indicate, e.g., changes in a particular stock price) and make decisions about when to buy or sell shares of stocks based on this data. In some cases, market data packets may include data on multiple different stocks, only a subset of which are analyzed by a particular server. In addition, a server may receive market data packets that only contain data not processed by that server. One source of inefficiency for these servers comes from identifying the useful data from the unnecessary data.